Turbine



Mmy14,1940.l A, YSHOLM 2,200,287

TURBINE 'Filed lay 8. 1937 Patented May 14, 1940 UNITEDA STATES2,200,281 TURBINE Alf Lysholm,

poration of Sweden Application May 8,

Stockholm, Sweden, assignor to Aktiebolaget Milo, Stockholm,

Sweden, a cor- 1937, Serial 'No. 141,388

InfGermany February 10, 1933 9 Claims.` (Cl. 253-39) This application isa continuation in partl with respect to my-copending application SerialNo. 710,465, .tiled February 9, 1934.

The present invention relates1to turbines and f has particular referenceto turbines intended to ,be operated with motive `iluid of relativelyvery high temperature. kStill more particularly the invention relates toturbines adapted tobe operated as parts of gas turbine systems and towhich 10 motive iiuid is admitted at an initial temperature of at leastapproximately 800 C. absolute.

When motive fluid is used which has an initial temperature of the labovenoted or higher value, difliiculties are encountered in maintainingpropy I ler clearances within the turbine and also in maintaining theparts of the turbine rotors as heretoiore constructed in rigidlyconnected relationship throughout the normal liie of the turbine. Suchdiilculties are largely traceable to the phenomenon commonly referred toas creep which occurs in the metals usually employed in turbineconstruction, whenthey are subjected to the combination of mechanicalstresses and extremes of temperature which obtain in high temu.peinture-turbines, particularly gas turbines.

'I'he general object of the present invention is to provide improvedturbine rotor construction of built-up form which will eliminate orsubstantially diminish the diiiiculties heretofore encoun- .n teredy inthe construction and'operation of turbines of the character underconsideration.

In accordance with the invention, the turbine rotor is built up of anumber of separate parts including a series of turbine discs to whichVthe 35- turblne blades are attached. 'I'he discs are annular in form andthe parts of the rotor are welded together atbr near the inner peripheryof the annular. discs so as to provide a hollow central shaft portionfor the rotor, whichvshaft oh portion includes asan integral partthereof the hub portions of the d iscs. y v

y The discs at the ends of the welded group forming the main part of therotor are welded to suitable ,end pieces to provide the necessary 45bearing support for the rotor. 1t will be understood,v oi course, thatthe construction With respect to end pieces for bearings will varydepending upon the type of rotor, for which the turbine isy intended.Such pieces may be at the ends 50 of the rotor in the case of the usualtype of axial iiow rotor having vbearings at its ends for its support.Other typesol" constructions having dierent bearing arrangements are.however,

contemplated within the scope of the invention.

u The invention may be carried into'eiiect'with ,different specificforms of construction, and its `more detailed nature'and the advantagesto be derived from its use may best be understood from a considerationof the ensuing portion of this specification and the accompanyingdrawing in "which are described and illustrated by way. oi

example, suitable forms of rotor construction for vcarrying theinvention into eiiect.

In the drawing:

Fig: 1 is a longitudinal central half section, 10 partly in elevation,of a turbine having a rotor embodying the invention in which the hubportions of the rotor discs are welded directly together to form theshaft portion of the rotor;

Fig. 2 is a fragmentary longitudinal central sec- `16 tion of rotordiscs directly welded together but oi other form; 'l

F'ig` 3 is a view similar to Fig. 2 but showing still another form ofrotor discs welded directly together: and

' Fig. 4 is a viewsimilar to Fig. 2 illustrating still another form ofconstruction embodying the I invention. l l

Referring now toFig. l, thefturbine illustrated is of the axial flowmultiple stage reaction type, .y the particular embodiment illustrated`being suitable for use as'a gas turbine adapted to operate at the veryhigh temperatures at which such turbines usually run.

The outer turbine casing l0 is of generally con- .0.

ical form and in the embodiment illustrated, is attached by means of aseries of radial pins l2 to an annular supporting member Il which is inturn secured to a second supporting member I6, the latter providingsupport for the rotor ,5'

bearing I8 at the inlet end of the turbine. An end member 20 attached tothe rear end of the casing l0 providessupport for the second rotorbearing 22.

Casing l0 supports a series of stationary blade 0- rings 24, suitablyspaced in axial direction to permit the rings of rotor bladesto beinserted therebetween.' The stationary blade ringsmay advantageously besecured to the casing I0 by means of radial pins 26, but ther particularmode 5f 'of mounting the stationary blades is not pertinent tothepresent invention or to an understanding thereof.

The rotor comprises a seriesof annular blade carrying discs 28 which attheir bases are thick- 50 ened laterally as at 30. The base portions 30of the discs are permanently secured together by means of weldsindicated `at32, and the end discs 28a and 28h are welded respectivelyto the annular end members 34 and 36 providing the journals 38 and 40which are supported by bearings i8 and 22, respectively.

As will be evident from the drawing, the thlckened base portions 30,when welded together, form a continuous hollow rotor shaft from whichthe discs 28 project. This form of shaft not `only produces a relativelylight rotor structure, but avoids the possibilityv of parts becomingloosened due to creep of the metal during the life of the turbine. Thehollow shaft construction also permits the ready admission of motive uidto the interior of the shaft to aid in obtaining uniform heating andexpansion of the rotor when the turbine is started from cold state. l

At the perimeters of the several discs 28 the moving turbine blades 42are attached. The specific mode of attachment may vary Within the scopeof the inventionbut the blades are preferably secured by welding, toprovide a completely integral rotor structure. 'I'he joints may bedovetailed as well as welded and as will be appreciated by those skilledin the art, the specific form' of the joint may be in accordance withnumerous known methods of attachment.

For purposes ofV illustration, a Vdove-tail or socket joint combinedwith weldingis diagramf matically indicated at 44.

In the drawing the usualtightening strips are indicated at 46, thesestrips sewing to minimize leakage between the moving blade discs of thevvv rotor and the stationary bladeringswhichepro- -ject radially inwardlybetween the rotating discs.

In the form shown in Fig. 2, the construction is the same as in Flg.- 1in so far"as the general assembly of the rotor is concerned.V In thepresent instance, however, the discs 28e are provided Y with inwardlyprojecting ange portions 48 vwhich project radially inwardly from thethickened portions 58 that are welded together as at 52 to form theshaft of the rotor. The inwardly projecting iianges 48 serve to reducethe stresses setup in the discsv due to centrifugal force and are alsouseful in aligning the separate discs in a jig or the like prior towelding the parts together;

Instead of making full butt welds of the kindv shown in Fig. 2, the hubsof the discs in certain instances may advantageously be shouldered asthe size and spacing oi the turbine discs which in some cases mayaccessible.

In Fig. y4 another form of construction is illustrated in which thediscs 28e are not thickened sumciently to permit their being weldeddirectly makea weld 88 relatively into eachother, in which case the hubsof the i discs have interposed between them a series of spacingrings 62.arranged so that the spacing rings and the hubA portions of the discstogether form the central hollow shaft portion of the rotor. Y

For ease and accuracy of assembly and welding, the hubs of the discs andthe spacing rings are advantageously flanged as indicated at 814 -andythe welds may be made either externally or internally of the rings asindicated at 68 and 68.

In the construction shown in Fig. 4 the rotor may be very readily andcomparatively cheaply constructed of rolled plate material, which whenof the kind of steel usually required for high temperature rotors, ismuch less expensive in sheet Y form than in the form of specialforgings.

From the foregoing it will be evident that within the scope `of theinvention the specinc designs hereinbefore described by way of examplemay be varied and the invention .fis to be understood as embracing allforms of-'construction falling within the scope of the appended claims.k

What I claim is:

1. For use in elastic huid-turbines, a. build-iup integral hollowl rotorcomprisingY a pluralityfof yturbine discs having different blade rootdiameters and a centralrhollow shaft portion'fsaid discsl beinggenerally symmetrical axially with respectL to' the respective centralplanes of the discs, said shaft portion being formed by axially abuttingparts including the hub portions of said discs and said parts beingunited by welding, saidshaftl portion constituting the sole meansfor-retaining Y the discs in axially assembled relation andfthe radiallyouter portions of sai'ddiscs being Vin `axi-v` s Y kZ5 ally spacedrelation. l 4

2., kFor use'in elastic iluid turbines, a build-up integral hollow rotorcomprising a plurality of turbine discs of progressively greater bladerootY diameter from the inletto the outlet endl of the"rotor'forcarrying blades providing a generally,v

conical Vpathof flow for expansion of motive u'id, and a central hollow'shaft portion of substantially uniform.A diameter, said discs rbeing'generg ally symmetrical axially with respect to thefrespectivecentral'plans of the discs, said'shaft portion beingformed byaxiallyabuttingparts including the hub'portions of said discs and saidpartsbeing united by, welding, said'shaft portion Y constituting thesole means `for retaining the rotor i parts in axiallyassembledrelation4 andthe vradially outer portions of said'discs being inlaxially spaced'relation.

3. For use inA elastic fluid turbines, a build-up f integral hollowrotor-comprising va plurality of turbine discs of diierent blade rootdiameter having hub portions thickened axially on each side of Vtherespectivecentral planesof the discs, to provide discs substantiallysymmetricalv with respect to-said planes, andacentral hollow shaftportion, said shaft'portion beingformed bythe axially abutting h'ubportions cfy the Vdi'scsjand welds uniting the abutting hubportions,.said4 Vshaft portion constituting the sole means formaintaining the discs in axially assembled 'rela- 1 being in axiallyspaced relation.

4. For us'e in elasticruidyturbines, a built-up integral hollow rotorcinprisingA a plurality oi' turbine discs having different bladeroot`diamtion and the radially outer portions of said discsV eters andhub portions thickened'in axial direc- Vtion at each side of therespective central planes of the discs, vto provide discs substantiallysymmetriCal'With respect to said planes, said hubs having shoulders attheir laxially opposite,V sides "to center them with Arespect toaxially-*adjacent K hubs ,and said abutting hubs being united `by awelds to form a central hollow shaft portion, said Y shaft portionconstituting the sole means*` for y tion and the radially outer portionsbeing in axially 'spacedrelation' `5. For use in elastic iiuid'turbines,a built-up of said discs discs having inner portions Vthickened axiallyon `maintaining the discs in axially assembled rela.- 1 70;V

`hollow rotor including a plurality of annularV .each side of therespective central planes of the 16" discs, to provide discssubstantially symmetrical with respect; to said planes, welds connectingsaid thickened portions to form a central shaft portion of the rotor,and flange portions projecting inwardly from the thickened portions ofthe discs, the flange portion and the radially outer portion ofrespective discs being substantially symmetrically located with respectto the central plane of the disc and the flange portion andthe radiallyouter portion of respective discs being axially spaced from thecorresponding portions of adjacent discs.

6. For use in elastic iluid turbines, a built-up integralV hollow rotorincluding a plurality of annular discs of increasing diameter axially ofthe rotor, said discs having hub portions of substantially the samediameter thickened axially on each side of the respective centralplanesof the discs, to provide discs substantially symmetrical withrespect to said planes, welds connecting said thickened portions to forma central hollow shaft portion ofV substantially uniformdiameter axiallyof the rotor from which the outer parts Aoi' said discs project radiallyin axially spaced relation, said central shaft portion providing thesole means for Vholding said discs in axially assembled relation, andflange portions on' `of the discs, and a plurality of annular spacingrings interposed between said discs and lwelded to the inner portions ofthe discs, the inner portions of the discs and said spacing ringsproviding a central hollow shaft portion for the rotor from which thediscs project and the portions of the ldiscs radially outside said shaftportion being in axially spaced relation.y

8. For use in elastic fluid turbines; a built-up hollow rotor having aplurality of annularv turbine discs, said discs being generallylsymmetrical axially with respect to the respective central planes of thediscs, and a plurality of annular spacing rings interposed between saiddiscs, the'radially inner portions of said-discs and-the ends of saidrannular turbine discs having dii'lerent blade root diameters and hubportions of substantially the same diameter thickened in axial directionat each side of the central planes of the discs, to

' provide discs substantially symmetrical with respect to said planes,said hubs having shoulders at their axially opposite sides to centerthem with respect to axially adjacent hubs and said hubs being united byinternal and external welds to form a central hollow shaft portion oi'substantially uniform diameter, said shaft portion constituting the solemeans for maintaining the discs in axially assembled relation and theportions of said discs outside said hub portions being in axiallyspacedrelation.

